1. Field of the Invention
The present invention relates to a hermetic packaging apparatus. More specifically, the present invention relates to a hermetic packaging apparatus in which the pressure in a thermoplastic packaging bag is reduced or increased or the packaging bag is filled with an inert gas and thereafter the opening of the packaging bag is heat-sealed by a heating material.
2. Description of the Prior Art
FIG. 1 is an outward perspective view of a conventional hermetic packaging apparatus and FIG. 2 is a cross sectional view of the same.
A conventional hermetic packaging apparatus will be described with reference to FIGS. 1 and 2. A power supply transformer, an air pump, a pressurizing link mechanism, a nozzle mechanism portion and so on are mounted on a metal base plate 1, though not shown. A top cover 2 covers the base plate 1 mounting these components from above and the cover is fixed to the base plate 1 by screws 10. An operation panel 3 having switches, adjustment handles, indicating lamps and so on necessary for operation is provided on the top cover 2. A nozzle 4 for deaeration, introducing air or for filling a bag with gas is provided such that it protrudes forward from the top cover 2 and this nozzle 4 is movable in forward and backward directions by a nozzle operating lever 5 protruding upward from the top cover 2.
In addition, a sealing base 11, an airtight packing 9 and a heating element 8 such as a heating wire are fixed below the nozzle 4 and in front of the top cover 2. An airtight pressure connecting bar 6, an airtight packing 7 and a seal packing 12 are provided and are movable in upward and downward directions by a link mechanism, not shown, above the nozzle 4 such that they are opposed to the sealing base 11. A table 14 is fixed to the sealing base 11 with screws 13. In hermetically sealing contents 16 in a package bag 15 using the hermetic packaging apparatus structured as above, a nozzle operating lever 5 is first pulled this side as shown in FIG. 2 so that the nozzle 4 protrudes on this side of the airtight packings 7 and 9. Then, the opening of the packaging bag 15 containing the contents 16 is put on the tip end of the nozzle 4 so as to cover the tip end with the bag, the nozzle 4 is surrounded by the packaging bag 15 and the opening end is inserted to the inner part of the sealing base 11.
Thereafter, the airtight pressure connecting bar 6 is pushed downward and the vicinity of the opening of the packaging bag 15 is held in an airtight condition by airtight packings 7 and 9 through the flat tube portion of the nozzle 4. Next, air in the packaging bag 15 is sucked and exhausted from the tip end of the nozzle 4 by means of a vacuum pump (not shown) or the like connected to the nozzle 4. When a package is to be filled with gas, gas is introduced on this occasion.
Then, the nozzle operating lever 5 is pulled backward rapidly, the nozzle 4 is extracted from the opening of the packaging bag 15 and, simultaneously, the airtight pressure connecting bar 6 is pushed further downward to connect the packaging bag 15 by the airtight pressure connecting bar 6 and the sealing table 11. In this state, a heating element 8 provided on the top side of the sealing base 11 is heated and the vicinity of the opening of the packaging bag 15 are connected by heat welding. After the heating, heat-sealing is accomplished after an appropriate time for cooling.
Other than the hermetic packaging apparatus structured as above, hermetic packaging apparatuses are known from Japanese Patent Publication Gazette No. 38959/1979 and U.S. Pat. No. 3,589,098.
In a conventional hermetic packaging apparatus as described above, the base plate 1, airtight pressure connecting bar 6, nozzle 4, screws 10 and 13 and so on, which are the portions easily accessed, are formed of metals. Therefore, if an insufficient insulation occurs due to some cause in the electric parts such as power supply transformer, air pump and so on, there is a possible danger of the metal portions becoming electric charging portions.
Meanwhile, some contents include a lot of water and others may be powder. The repeated sucking of such water and powder may cause a jam of powder or the like in the nozzle 4, air pump, strainer and an airtight pipe connecting these portions, causing a failure, a nasty smell, or the reproduction of various germs.
In addition, the contents 16 in the packaging bag 15 may be spilt on the base plate 1 by accident during operation. In such case, if the content 16 is a broth including salt, for example, the broth enters from the front opening A of the top cover 2 affecting the electric parts of the apparatus.
In the conventional hermetic packaging apparatus, the nozzle operating lever 5 should be pulled to this side and after the decompression, pressurization or the filling of the packaging bag 15 with gas, the nozzle operating lever 5 should be again pulled backward manually every time the content 16 is packed in the packaging bag 15. It is troublesome to operate the nozzle operating lever 5 every time. In addition, the nozzle operating lever 5 must be rapidly operated after the decompression, pressurization or filling with gas in order to hold the airtightness.
Furthermore, the strainer tank must be removed or the plug provided in the strainer tank must be removed after several operations, in order to dispose of the stagnant liquid in the strainer tank.
In the above described conventional hermetic packaging apparatus, the contents 16 in the packaging bag 15 may be shifted during heat-sealing, so that the contents 16 can not be sealed easily. As for the contents including water, the water is sucked by the nozzle 4 into the pump.